Safety mechanism for rotary projectiles

ABSTRACT

A SAFETY MECHANISM FOR ROTATING PROJECTILES COMPRISING A MEMBER CARRYING A PORTION OF THE CONVENTIONAL PYROTECHNIC TRAIN AND DESIGNED TO BE SHIFTED, AFTER BEING RELEASED BY A LOCKING DEVICE, UNDER THE ACTION OF THE CENTRIFUGAL FORCE DURING THE FLIGHT OF THE PROJECTILE.

Sept. 20, 1971 P. A. THEATE SAFETY MECHANISM FOR ROTARY PROJECTILES 2 Sheets-Sheet 1 Filed June 25, 1968 8 3a 4 hwh l w F. 4, j 1 WW. 3 fla #32 \x a U 4/ 0? V PAILL Alt MM TMA TE INVENTOR.

Sept. 20, 1971 P. A. THEATE SAFETY MECHANISM FOR ROTARY PROJECTILES 2 Sheets-Sheet 2 Filed June 25, 1968 7m L M2222 T/M'A TF I N VE N TOR atent 3,605,623 Patented Sept. 20, 1971 hoe 1,110 Int. Cl. F42c 9/02, 15/22 [7.5. Cl. 10279 7 Claims ABSTRACT OF THE DISCLOSURE A safety mechanism for rotating projectiles comprising a member carrying a portion of the conventional pyrotechnic train and designed to be shifted, after being released by a locking device, under the action of the centrifugal force during the flight of the projectile.

This invention relates to a safety mechanism for projectiles rotating about their axis during the flight thereof.

Several safety mechanims have already been proposed, which all substantially comprise means providing for the discontinuity of the firing of the pyrotechnic train, the constituting elements of the latter being all in alignment only when the projectile is on its trajectory at a certain distance from the mouth of its launching tube. For this purpose, numerous known devices use a clockwork mechanism released by the withdrawal of a lock under an inertia effect at the start, said mechanism bringing for instance the striker into alignment with the remaining pyrotechnic train after a given time determined to obtain the desired safety at the beginning of the trajectory.

These known mechanisms are generally operating satisfactorily, but they are disadvantageously very complex and thus expensive and often delicate.

The object of the present invention is to prevent these drawbacks by providing a relatively very simple mechanism, wherein the release of a moving element bearing an element of the pyrotechnic train, the time at which this release occurs and the shifting of the said moving element in active position result from the centrifugal force created by the rotation of the equipped projectile about its axis during the flight.

More specifically, the safety mechanism according to the invention comprises substantially a slide hearing at least one element of the pyrotechnic train, said element moving in a direction perpendicular to the projectile axis, the shifting of the slide under the effect of the centrifugal force being momentarily prevented at least by a lock the withdrawal of which is actuated by the controlled shifting of a mass which, under the centrifugal force is carrying out a rotation and translation movement respectively about and along an axis situated in a plane perpendicular to that of the projectile.

The characteristics and the advantage of this invention will be more apparent by the following detailed description of a preferred embodiment given only by way of illustration, reference being made to the enclosed drawing in which:

FIG. 1 is an axial section of a mechanism according to the invention mounted within the body of a projectile; FIG. 2 is a section along the line II-II of FIG. 1;

FIG. 3 is a section on an enlarged scale along the line III-III of FIG. 2;

FIGS. 4 and 5 are sections similar to that of FIG. 2, showing the mechanism according to the invention in two characteristic successive operating positions.

As shown in FIG. 1, the mechanism 1 according to the invention is disposed in a housing 2 formed by the casing 3 of the projectile and a partition 4 to which mechanism 1 is fastened.

The mechanism 1 is housed in the bottom 5 of a casing the lid 6 of which carries a relay-charge 7 disposed upstream the main explosive charge 8. The cylindrical bottom 5 is provided with a diametral groove 9 in which may shift a slide 10 hearing one element of the pyrotechnic train, namely the detonator 11. This train is completed by a priming 12 disposed in a housing 13 provided in the said bottom 5 and approximately in the center thereof.

This slide 10 is normally brought to standstill in the position represented in FIG. 2 by a pair of diametrically opposite locks 14 and 15 engaging respectively notches 16 and 17 provided on the opposite side faces of the slide 10. Each of said locks 14 and 15 is freely housed in a radial bore provided in the bottom 5 (1S and 19 respectively), said bores being coaxial. In addition, each of the said locks is provided with a cylindrical mass 20 and 21 respectively which may slide in the corresponding bore like a piston. The said locks are permanently actuated to their locking position by springs 22 and 23 bearing respectively, on one hand, upon the said masses 20 and 21, and on the other hand, upon the end of the screws 24 and 25 obturating the bores 18 and 19 respectively.

One of the said faces of the slide 10 is also provided with a notch 26 into which penetrates normally the end of a lock 27 carried at the end of a rod 28 passing through a hollow rod 29 coaxial with the latter. One end of the said hollow rod 29 is threaded and is screwed in a threaded radial bore 30 provided in the said bottom 5. The said bore 30 is extended outside the bottom 5 by a bore 31 having a larger diameter, which is, in turn, extended by an external chest 32.

The lock 27 is permanently actuated to its locking position by a spring 33 surrounding the said rod 28, housed in the hollow rod 29 and bearing upon the bottom 34 of the latter. The free end of the rod 28 is provided with a washer 35 applied against the end of the hollow rod 29 and being outside the same when the lock 49 is in locking position, the diameter of the washer 35 being larger than the external diameter of the said rod 29.

The external cylindrical surface of rod 29 is provided with a thread under the form of a helical groove 36 engaged by the balls 37 of a nut 38 housed about the said rod 29 in the bottom of the bore 31 when the lock 27 is in locking position. This nut has an annular shoulder 39 and it is normally brought to standstill at the bottom of the bore 31 by a lock 40 engaging the said shoulder 39, said lock projecting from the wall of the bore 31 and extending into a bore 41 perpendicular to the axis of the said bore 31. The lock 40 is permanently actuated into its release position by a spring 42 bearing, on one end, upon the bottom of bore 41 and, on the other end, upon a head 43 integral with the said lock 40. The latter is nevertheless held in locking position by the engagement, in the said head 43, of one end of a pendulum 44 pivoting freely at 45 in a bore 46 bringing the bore 41 into communication With groove 9, the other end of the said pendulum projecting in the said groove 9 and being applied against a flange 47 of the end of the slide 10. The latter is provided with a ballast 48.

The above described mechanism operates as follows: at rest, the mechanism is in the position represented in FIG. 2 in which the slide 10 is maintained by locks 14 and 15 so that the detonator 11 lies out of alignment with the remaining pyrotechnic train consisting, on the one hand, of a relay-charge 7 and, on the other hand, of priming 12.

When firing or launching the projectile, the rotation movement of the latter about its longitudinal axis causes,

at the very outlet of the barrel, the withdrawal of locks 14 and 15 under the centrifugal force acting upon the mass of the latter and the pistons 20 and 21 thereof. In this way, the slide 10 is released and, under the centrifugal force acting upon its center of gravity, brought out of center by the presence of ballast 48, and it is shifted in the groove 9 until the lock 27 comes into contact with the other face of notch 26, the width of which is at least equal to the sum of the diameter of lock 27 and the width of shoulder 39 of nut 38. This shifting of the slide 10 allows the pendulum 44 to pivot under the action of spring 42 and the centrifugal force, thereby withdrawing simultaneously lock 40. In this way, nut 38 is released and, under the action of the centrifugal force, it is shifted with a rotating movement along the hollow rod 28. The mass of nut 38, the pitch of the helical groove 36 and the length of rod 29 are provided in accordance with the extent of the delay or the desired mouth safety so that the said nut pushes back the washer 35 and, hence, the lock 27 against the action of the spring 33 after this delay time. The withdrawal of lock 27 causes the complete release of slide 10 which may then occupy the position represented in FIG. in which the detonator 11 is in alignment with the remaining pyrothechnic train.

In addition, the shifting of slide in groove 9 may be also used to provide additional safety functions. Thus, in the represented embodiment, the safety mechanism according to the invention is particularly designed for equipping a projectile provided with a target detecting unit together with a mechanism for correcting the trajectory by the lateral ejection of an added projectile. In that case, the slide 10 may be also used as a safety switch for closing the electric priming circuits 12 of the detecting device and the priming circuits of the projectile correcting the trajectory (not shown) only when the projectile has travelled a distance corresponding to the required safety time. For this purpose, deformable contacts the number of which depends upon the number of circuits being controlled and indicated jointly in 51, are disposed on both sides of the longitudinal symmetry plane of groove 9, whereas a small plate of insulating material 49 carrying conductors 50 connecting both opposite faces thereof is mounted at the end of the slide 10. At the end of the stroke of slide 10, the small plate 49 comes between contacts 51 which are then closed by the respective conductors 50-. To provide a permanent closure of the said contacts together with a positive locking of the slide 10 in active position, the said contacts 48 may be provided with a plurality of teeth 51 cooperating with the corresponding notches 52 provided in the said conductors 50 or the small plate 49'. Alternately, an additional lock could also fulfil this function.

It is of course apparent that numerous modifications may be brought to the above described mechanism without departing from the scope of the present invention. Thus, the constituting elements of said mechanism illustrated hereabove may be replaced by other elements having equivalent functions, it being possible to adapt the respective position of said members in accordance with the projectile type being equipped.

What I claim is:

1. A safety mechanism for projectiles which rotate about their axis during flight, comprising a pyrotechnical train having two portions, a member carrying one of said portions and adapted to be shifted under the action of the centrifugal force during flight to bring said one portion into active position or alinement with the other portion, a lock preventing the shifting of said member up to the active position, means including a mass and causing controlled shifting of said mass along an axis under the centrifugal force at the initial stage of the flight for withdrawing said lock, and an electric circuit having contacts for closing the circuit, said member having a plate engaging said contacts and closing said circuit when said member reaches the active position.

2. A detonating fuse device for rotating projectiles, comprising a pyrotechnical train having two portions, a slidable member carrying one of said portions and having an inactive position in which said one portion is out of alinement with the other portion, said member being shifted by centrifugal force caused by the rotation of the projectile in flight to an active position wherein said one portion is in alinement with the other portion, means responsive to the centrifugal force for locking said slidable member in said inactive position and delayedly unlocking said slidable member upon the firing of the projectile, and at least one electrical circuit, said means comprising a lock engaging said member in said inactive position, a mass, means guiding said mass radially to the axis of the projectile and causing the mass to carry out a translating and rotary movement while the mass is subjected to the centrifugal force and yielding abutment means located in the path of said mass and connected to said lock to withdraw said lock when engaged by said mass.

3. A detonating fuse device according to claim 2, wherein said lock comprises an axially movable rod extending radially in the fuse device and having one end engaging a notch of said slidable member in the inactive position, the other end of said rod carrying said abutment means.

4. A detonating fuse device according to claim 3, having a supporting part and wherein said guiding means comprise an externally threaded tube enclosing a portion of said rod between said abutment means and said supporting part.

5. A detonating fuse device according to claim 4, wherein said mass has an axial bore traversed by said tube, said mass having means within said bore for engaging the external threads of said tube.

6. A detonating fuse device according to claim 4, having spring means located within said tube and pressing said rod toward its locking position.

7. A detonating fuse device according to claim 2, comprising electrically conductive contactor means carried by said slidable member and closing said electrical circuit when said member is in its active position.

References Cited UNITED STATES PATENTS 2,790,390 4/1957 Baker 102-79X 2,921,526 1/1960 Hamilton 102-79 3,264,995 8/1966 Libby et a1 10279 BENJAMIN A. BORCHELT, Primary Examiner J. I. DEVITT, Assistant Examiner US. Cl. X.R. l0271 

